This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Tomographic phase microscopy (TPM) is a unique device that combines the quantitative phase imaging with tomographic method for 3-D reconstruction: quantitative phase images are taken at multiple illumination angles of an incident beam and the 3-D refractive index map is reconstructed by numerically processing the 2-D phase images. Three dimensional imaging of a live cell provides a way to investigate optical properties of individual organelles. The aim of the project is to measure refractive index map in live cells with high spatial resolution and accuracy. The challenges involved are diffraction from internal organelles and limited angular coverage of the incident beam.